David had 96 coins. ⁵₆ were green and the rest were yellow and pink. The ratio of the number of yellow coins to the number of pink coins was 1 : 3. David decided to give away some green coins to decrease the number of green coins to half of the total number of coins.

1. How many more green coins than yellow coins did he have at first?
2. How many green coins did he have to give away?

Green coins	Yellow coins	Pink coins	Total
5x4	1x4
	1x1	3x1
20 u	1 u	3 u	96

	Green coins	Yellow coins	Pink coins
Before	20 u	1 u	3 u
Change	- ?
After	4 u	4 u
Comparing green, yellow and pink coins in the end	1	1

(a)
The total number of yellow coins and pink coins is repeated. Make the total number of yellow coins and pink coins the same.  LCM of 1 and 4 is 4.

Total number of coins at first
= 20 u + 1 u + 3 u
= 24 u

24 u = 96

1 u = 96 ÷ 24 = 4

Number of more green coins than yellow coins at first
= 20 u - 1 u
= 19 u
= 19 x 4
= 76

(b)
Number of more green coins that David had to give away
= 20 u - 4 u
= 16 u
= 16 x 4
= 64

Answer(s): (a) 76; (b) 64